What is Unlocked Cell Phone?
A cellular or mobile phone usually has a feature that allows for its use only with specific service providers or only in specific regions. When service providers such as for example AT&T, Sprint, T-Mobile etc. acquire a batch of cellular phones from i.e. Nokia, Sony Ericksson, the phones are then locked so that they can only be used exclusively with SIM (subscriber identity module) card from that one service provider. Mobile phone service providers usually do this because they give out deals wherein subscribers get a steeply discounted rate for a handset (or even give the handset for free) in exchange for a subscription contract which usually lasts for 1-2 years. To ensure that subscribers will continue to use their service and to make sure that they can recover their investment from attracting customers, phones are locked only for use with one specific brand of service provider.

There is a way however, for a cell phone to be unlocked. A handset can usually be unlocked by entering a special unlock code which can be manually entered or sent over the air by a service provider. Phone companies usually keep this information confidential, but there have been many leaks and software that now allow hackers to unlock phones for a fee. An unlocked cell phone is a handset which can be used with any mobile phone service provider and in any country or region.